Starter-generator gearing for internal-combustion engines



P 5, 1949- e. MAURIC ETAL 2,466,461

STARTER-GENERATOR GEARING FOR INTERNAL-COMBUSTION ENGINES Filed Aug. e,1946 1 vu on 0 4 GERHARD MAUR/C NA THAN/EL L Ros/N RALPH E GREENPatented Apr. 5, 1949 UNITED STATES PATENT OFFICE STARTER-GENERATORGEARING FOR; INTERNAL-COMBUSTION ENGINES Gerhard Mauric and Ralph E.Green, Los Angeles, and Nathaniel L. Rosin, Hollywood, Calit, assignorsto Electrical Engineering and Manuiacturing Corporation, Los Angeles,Calif., a corporation of California Application August 6, 1946, SerialNo. 688,646

1 Claim. (Cl. 74-6) 2 This invention relates in general to devices andsystems for starting an internal combustion engine and for generatingelectric energy during the operation of the engine by power deriveddriving the crankshaft to start the engine, and

being operable to cause the electric machine to be driven at a suitablespeed when the engine has started and is driving the electric machine asa generator. tofore been most widely used on automobiles they are usefulwith all internal combustion engines, regardless of the use or typethereof and are, of course, useful on aircraft. In this latter field ofuse, however, rigid standards'oi weight, f reliability and simplicityare imposed which have not heretofore concerned those skilled-inthis artp p, )1 H v v I x v "20- e ha and tht' rahk hefli t l the Ou p a of'theredtiotion' gearing assmblyiftocause the; In one of its principalaspects this'inventiony relates to the general structure and arrangementof parts of devices' 'of the't'isoribed' type ari'd has and it has beenfound that many known device are entirely unsuitedto aircraftf I for oneof its principal ffobjects the provision a starter-generator devichavii' g not'only antihimum number of parts but- {utilizing 'only' -thsimplest of mechanisms and components; where by the weight ithe-device:is kept {minimumand the ease ojfrep'airjanj is advanced, 'thus"'niakingdevise transect this invention particularly" useful in the aircraftfield although not limited thereto in anyivayi" 4 connection with thissweeten-themention, it

While such devices have here'-v Referring to the drawings, in whichsimilar reference numerals refer to like parts,

Fig. 1 is part-sectional view showing, schematically, an internalcombustion engine, an electric 5 machine which is operable to start theengine and is also operable as a generator, and showing moreparticularly the power-transmitting mechanism connecting the engine andthe electric machine, and

10 Fig. 2 is a view showing the power-transmitting mechanism with theparts in the position occupied when the motor-generator is starting theengine.

In carrying the invention into eilect ther is 15 provided a reductiongearing assembly having an input gear which is drivingly connected tothe rotor of an electric machine, which may be operated as a motor orgenerator, and also hav-' ing an output gear. There is also provided ago shaft which is drivingly connected to the crank f shaft "of anintemal 'fcombustio'ri engine, and with shaft are associatedtwoclutch'devices, one oi! which is operable" when the electric ma."

chine-is operated asastarter motor-to connect 0. lsi ii has been oneransom-sets td'pro'v ide a startergenerator device "ha ving-= aparticularlyimpie 18% a w t power-transmitting: gearing-wrath wm itotunw clude the complicated-gear arrangementsand a one-way rollerfclutch"devices ri -struc 4 r" *y tsm 1 Q catnksn it unseat 'tea,""9ide"r-"to"'be startd. These objects a d other nheren-t in the invengo, zq s'gi' ha bf tg m u v m tion' have been realiz'ed i bythisiriveiition and m flds'rifs gorgfiefiblltfiafiiwfie'nii areincorporatedin'aiiemliodiment therof whichth'iih *ist 'mfiaffd a "g-i it fig is discl sed in, the followin c p iolfandfth fio poiver tfieWriiatiireftif th' filetrifliiachihe wilt; annexed drawing-s he isd bs reofft ?'nfretatd at ai "iiitable' speed td"cause' stich i Ierredembodimiit is ior ptirposes of;i1iustratiefi' mdme toigfigi'atieletflc'enrgy ere 'atm t; f he nvention only. andilii'Doses'did}iririltationsfit c -preferably tif the usuali structureo i on the invention not mpos'edb he pprided? a, motor or generator, comprising a statoraiid at; claim68 rotating ai'hrature supporteddn' earings ta sit-3 it: tie mi? beingenclosed in a casing 6. The end of the I armature shaft 8 adjacentbearing 4 extends into a housing iii which is attached to the end of thecasing and within which the powertransmitting mechanism is housed.

The power-transmitting mechanism comprises a rotatable shaft 28 one endof which is freely and rotatably journaled in a recess in the end ofarmature shaft 8 and the other end of which is external to casing 10 andis provided with a pinion gear 22 which is operably connected to thecrankshaft 23 of the internal combustion engine B through means externalto the housing ill, such as the timing gear 25. Intermediate its endsthe shaft is supported by gearing 24 in the wall of housing i0. Withinhousing i0 and adjacent the end of the armature shaft 8 a pinion gear 28is freely and rotatably mounted on shaft 20 and is drivingly connectedto armature shaft 8 through a torque-limiting connection 21 which ispreferably of the type and structure described and claimed in theco-pending application of Gerhard Maurie, Serial No. 688,645.

The pinion gear v28 meshes with a gear 28 which is keyed to a Jack-shaft80, which also comprises a pinion gear 82 which is in mesh withat restand that it is desired to start the internal combustion engine 13, theparts will be found in the positions shown in Fig. 1, and current may beapplied to the motor-generator A to operate the same. The rotation ofarmature shaft 8 will be transmitted'to pinion gear 26 through thetorque limiter 21. causing rotation of gear 34 through the reductiongearing. Until-this a gear 34 which is freely and rotatably mounted.

on shaft 20. ,It will be apparent that the gear train 28, 28, 32, 34will provide a speed reduction whereby rotation of pinion gear 26 will30 cause gear 24 to be rotated at a speed less than that of the piniongear.

Means are provided by the invention for transmitting the rotation of thearmature shaft 8 and pinion 28 to shaft 20, through the describedreduction gearing and, under other conditions, for transmittingthe'rotation. of crankshaft 23 and shaft 20 to pinion 26 :and-thearmature shaft without the interposition of the reduction gearing.Suchmeanscomprise a disc 40 which is rigidly connected topinion gears 26and has an internal frusto-conical clutch surface. This part time shaft28 will be held from rotation by the inertia ofthe internal combustionengine B, the clutch surface on member 48 will be in engagement with thecorresponding surface of pinion disc 40. and the clutch surfaces on conenut 44 i and gear 34 will be separated, having been left in suchcondition on the earlier stopping of the engine. Rotation of pinion gear26 will be transmitted through friction surfaces 40 and 46 and willcause cone nut 44 to move axially into contact with gear 44. The partswill now be in the position shown in Fig. 2. Rotation of gear 34 willnow cause cone nut 44 to tighten against gear 34, thus locking these twoparts together and causing the rotation of gear 34 to be transmitted toshaft 20. The crankshaft of the engine will therefore ,be rotated at thereduced speed provided by the reduction gearing, thus starting theengine. The relation of the parts is such that any rotation imparted tomember 46 by the pinion disc at this time will tend to cause the conenut 44 and member 48 to move to the right on shaft 20, by reason ofwhich there is no direct transmission of rotation from pinion 26 toshaft 20, such shaft being rotated only through the 35 reductiongearing.

will cause relative rotation to take place between is referred to inthisapplication as the pinion disc." A similarinternal, frusto-conicalsurface is formed on gear 24 and faces the cone surface on the piniongear 24 the shaft "has a quick-action thread 42 formed thereon toreceive the correspondingly threaded sleeve, of a cone nut" 44 having afrusto-conical surface facing the cone surface on gear 34 and adapted tobe moved into and out of engagement therewith by relative rotation ofshaft 20 and the cone nut. A member 48 surrounds the sleeve of cone nut44 and is splined thereto whereby it must rotate therewith but can moveaxially thereof. This member 48 has a frusto-eonical surface facing thaton the pinion disc 40 and is normally held in engagement therewith by acoil compression spring 48 surrounding the cylindrical sleeves of conenut 44 and member 46. An annular flat spring I0 is disposed between conenut 44 and member 48 and normally exerts no force on these members, butis adapted to yieldinsly resist movement of such members towardeach'other in order to prevent damage to the power-transmittingmechanism 0 and the electric machine A in the event the engine backiiresduring or after stopping. Reference is made to the aforesaid copendingapplication of Gerhard Maurie for a full disclosure of the mode ofoperation of the parts. including spring I.- bsckflre. The operation ofthe mechanism will now be described. Assuming that all of the parts aredisc. Between the pinion disc and shaft 20 and cone nut 44 which willcause the cone nut to run up the threads 42 in a direction away fromgear 14, thus relieving the'connection between these parts andcompressing the coil spring 48. The parts will now be in the positionshown in Fig. l. The clutch surface on member will therefore be forcedinto tight engagement with the corresponding surface on pinion disc 40,whereby the rotation of the engine crankshaft and shaft 20 will betransmitted through threads 42, cone nut 44, member 48, pinion disc ll,pinion 2i and torque limiter 21 to the shaft 8 of the motor-generator A,operating the same as a generator. The gear 84 is disconnected fromshaft 20 by movement of the 'cone nut 44 away from it, and the reductionin the event of such I gearing 28. ll, 22, 84 merely idles when theengine drives the generator.

It will be seen that the described and illustrated device will operatecompletely automatically to effect the desired starting of the engine oroperation of the electric machine as a generator of electricity,performing these functions with a minimum number of parts. all of whichare of simple construction and arrangement. The use of roller clutchesis completely avoided, as is the requirement of any manual controlmeans.

While we have described and illustrated but one embodiment of ourinvention it will be apparent to those skilled in the art that otherembodiments. as well as modifications of that disclosed. may be madewithout departing in any way from the spirit or scope of the invention,.

for the limits of which reference must be had to the appended claim.

What is claimed is:

A starter-generator for internal combustion engines, comprising arotatable shaft adapted to be drivingly connected to the crankshaft ofan engine and having a threaded portion, a reduction gearing assemblyincluding an input gear adapted to be drivingly connected to the rotorof an electric machine and an output gear both of which are freely androtatably mounted on the shaft at opposite ends of said threaded portionand have spaced, facing clutch surfaces formed thereon, a clutch memberhaving a sleeve part threaded to the'shaft and having a clutch partadapted to move into and out of clutching engagement with the clutchsurface on the output gear of the reduction gearing assembly bythreading of the clutch member with respect to the shaft, and a secondclutch member having a part surroi'incling and keyed to the sleeve ofthe first clutch member for rotation therewith and axial movement withrespect theretorand- GERHARD MAURIC.

RALPH E. GREEN.

NATHANIEL L. ROSIN.

REFERENCES CITED The following references are of record file of thispatent:

FOREIGN PATENTS in the N umber Country Date 430,044 Great Britain June12, 1935 687,056

France Apr. 22, 1930

